Facing the Rams at full strength is hard enough. Doing so without some key contributors, as the Saints will have to do Sunday, only makes advancing to the Super Bowl more difficult.

Of the four teams set to play in the highly anticipated conference championship games, the top-seeded Saints have the biggest injury problems, starting with the absence of stud defensive lineman Sheldon Rankins, who tore his left Achilles tendon in last Sunday’s divisional round win over the Eagles and was placed on season-ending injured reserve.

Wide receiver Keith Kirkwood (calf), who caught a key touchdown against Philadelphia, has been ruled out, and tight end Ben Watson (illness) is questionable, though ESPN reported he will be inactive due to appendicitis.

Also, offensive linemen Andrus Peat (hand), Ryan Ramczyk (shoulder) and Max Unger (knee), while expected to play after all practicing fully Friday, are each dealing with injuries.

Before the injury, the 24-year-old Rankins was ranked by Pro Football Focus as the 21st-ranked defensive tackle in the NFL. He had notched 15 quarterback hits, 12 tackles for loss and eight sacks. In a 45-35 Saints victory over the Rams on Nov. 4, the Rankins-led front seven held Los Angeles to 92 rushing yards on 19 carries.

“He created a lot of mismatches on the offensive line and was somebody that had to be accounted for,” Saints coach Sean Payton said of Rankins this week. “But [he’ll] definitely be missed, but it’s a next man up league. That is just the nature of the business that we are in.”

Even without Rankins for three quarters, the Saints held the Eagles to just 49 rushing yards. But the Rams, led by Todd Gurley and C.J. Anderson, are a different animal. They punished the Cowboys last Saturday on the ground for 273 rushing yards and three touchdowns. The Saints, however, haven’t allowed more than 112 rushing yards in a single game, and no rusher has had more than 75 yards.

“It’s going to be a physical game,” said Taylor Stallworth, one of the key replacements for Rankins. “We’re already getting prepared for that.”